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Multiple Choice
Of the visible light spectrum, the rate of photosynthesis is greatest under which color light?
A
Yellow
B
Red
C
Blue
D
Green
Verified step by step guidance
1
Understand the relationship between light and photosynthesis: Photosynthesis is driven by light energy absorbed by pigments in the chloroplasts, primarily chlorophyll a and chlorophyll b. These pigments absorb specific wavelengths of light more effectively.
Recall the absorption spectrum of chlorophyll: Chlorophyll absorbs light most efficiently in the red (around 650-700 nm) and blue (around 430-450 nm) regions of the visible spectrum. It reflects green light, which is why plants appear green.
Analyze the options: Yellow light is less effective for photosynthesis because it is not strongly absorbed by chlorophyll. Green light is the least effective because it is mostly reflected, not absorbed. Red and blue light are the most effective for driving photosynthesis.
Compare red and blue light: While both red and blue light are effective, red light is often slightly more efficient for photosynthesis because it is absorbed by both chlorophyll a and b and is used in the photosystems to drive the light-dependent reactions.
Conclude based on the evidence: The rate of photosynthesis is greatest under red light, as it is absorbed efficiently and contributes significantly to the energy required for the photosynthetic process.